Your RPM vs MPH (1 Viewer)

[HMP]

Maybe I just dont know the old FJ drivetrain well, Ive put very few miles since buying. But Im wondering where yall are on the tach vs what mph.
I just dont 'feel' the car shifting that much and wanted some confirmation if things were ok or not.
I know tire size will makea difference, mine is on 31x10x15 currently

Just looking for some help here, I really appreciate it

 

[CaptHamster]

That depends on which model you have...looking through your post history, I'm guessing you have an FJ62 with the 3FE, A440F automatic transmission and factory 4.11 diff gears.

That tach vs. MPH combo depends on all the above factors, as different 60 series rigs had different transmissions with different gear ratios in the diffs. When my FJ62 was stock on 31" tires, I was running about 2100RPM at 65MPH. That was in 4th gear (overdrive) with the torque converter locked up. The shifts weren't buttery smooth but I could certainly feel the shifting of each gear, and could definitely feel the torque converter lockup, which dropped maybe ~300RPM?

There are some good gear ratio calculator websites/excel sheets floating around out there; one I found on this forum I think was titled "gearsmud.xls" or something like that, and included different options so you could see what your RPMs would be with a given setup.

 

[HMP]

That depends on which model you have...looking through your post history, I'm guessing you have an FJ62 with the 3FE, A440F automatic transmission and factory 4.11 diff gears.

That tach vs. MPH combo depends on all the above factors, as different 60 series rigs had different transmissions with different gear ratios in the diffs. When my FJ62 was stock on 31" tires, I was running about 2100RPM at 65MPH. That was in 4th gear (overdrive) with the torque converter locked up. The shifts weren't buttery smooth but I could certainly feel the shifting of each gear, and could definitely feel the torque converter lockup, which dropped maybe ~300RPM?

There are some good gear ratio calculator websites/excel sheets floating around out there; one I found on this forum I think was titled "gearsmud.xls" or something like that, and included different options so you could see what your RPMs would be with a given setup.

Great post, THANK YOU
I'll drive it again and see where my rpms are at 65mph
If it's not getting to 4th and dropping the rpm to that, well, rpm...what would be the solution?

 

[Michael Hanson]

Hi, 31s are really not much of a change from stock. On our fj62s We saw not much change in driving . 33s was a noticeable change.

 

[CaptHamster]

Well if you're at 65MPH and you're rolling at, say, 2800RPM, there's a few different ways that could go:

A.) You're in 3rd gear, not in "D" (which would allow the 4th overdrive gear)
B.) You're in 4th gear, but slipping out of torque converter lockup or out of 4th altogether
C.) Your speedometer is way off and you're not actually going 65MPH

If you're not around the neighborhood of 2,000RPM to 2,200RPM at 65, the first thing I would check would be the transmission fluid condition and level when hot; these auto transmissions are very sensitive to incorrect fluid levels and will act wonky if it's not right.

Drive the truck at highway speeds for 20-30 minutes, really get it warmed up; pull back into the driveway and with the engine running, pull the transmission dipstick and check the fluid. It should be nice and red, slightly sweet smelling, and the level should be between the two lines with the word "HOT" in the middle. If it's clean but low, add more ATF through the dipstick hole. If it's black or brown, smells burnt or is otherwise gross, I would look into a drain and fill at the very least.

If the fluid checks out okay, the next thing I would get is a FSM (factory service manual, downloadable versions found on this website...) and start looking into adjusting the shift linkages or adjusting the kickdown cable. Lots of topics on both in this forum, search around if needed and you'll find what you need.

Good luck; the A440F auto transmission doesn't get the best reputation around these parts but they are tougher than they get credit for. I ran mine low on fluid, overheated it constantly and rebuilt it once, got 30ish years and probably 250K miles out of mine which would have totally killed most other auto transmissions. Now I have a 5 speed manual which I like much better, but that doesn't mean I didn't like the auto...

 

[HMP]

2k rpm at 55mph is what Im getting.
I put it in 3 and the rpms went up, so it IS in 4th, apparently